K-mixers are high intensity mixers (see U.S. Pat. No. 4,332,479 to Crocker et al.) that can be used, among other applications, for mechanical regenerating of rubber (see U.S. Pat. No. 5,883,140 (Fisher et al.); U.S. Pat. No. 7,342,052 (Fulford et al.); or Applicant's application WO 2011/113148). K-mixers differ from agitators and kneading apparatuses in that they can be operated at higher RPMs (revolutions per minute) and high moments of force (torque). Their components are thus subjected to high temperatures, and in rubber regeneration applications, the thermal inertia of the components prevents operating the K-mixer in a semi-continuous process environment. A semi-continuous process is typically a batch process which can be realised without having to stop or minimally stopping equipment in between batches. In order to mitigate this problem, a cooling jacket can be provided around the mixing chamber and/or a coolant can be circulated in the shaft. While these solutions help to alleviate problems related to over-heating in the K-mixer, they are still insufficient for some applications, especially for rubber regeneration.
Agitators, kneaders, bladed rotors or other sorts of apparatuses including temperature-controlled systems have been disclosed in the past, such as in U.S. Pat. No. 4,040,768 (Christian); U.S. Pat. No. 4,856,907 (Moriyama) or U.S. Pat. No. 7,540,651 B2 (Matsumoto et al.). However, none of these US patents discloses temperature-controlled systems adapted for K-mixers.
Referring to U.S. Pat. No. 4,856,907 to Moriyama, a kneader is disclosed. The kneader has a shaft 5 on which external members 7 are fitted. The rotor shaft 5 is provided with heat transfer passages 13, 14 linked to spaces 9 of the blades 10, which are integrally formed by the external members 7. As shown in FIG. 2 of the patent, the passages 13, 14 of the shaft 5 are located on the central axis of the shaft, meaning that the outer periphery of the shaft where there are no blades is not thermally-controlled by the heat transfer liquid. In addition, the space 9 of the blades is completely hollow, the heat transfer liquid freely circulating in the space, which is does not provide for an efficient flow of fluid within the blade. In addition, the flow of fluid within the external members 7 cannot be adjusted.
Referring to U.S. Pat. No. 7,540,651 to Matsumoto et al., an agitator is disclosed, especially adapted for agitating fluids, such as inks and coloring liquids. The agitator includes a rotating shaft 3 and a flat paddle blade 4. The shaft 3 includes inner and outer pipes 3a, 3b, and an integrally formed paddle with a passage 12 for a coolant medium. The passage 12 zigzags in the paddle, which results in the coolant circulating in different directions, clockwise and counter-clockwise, within the paddle. The configuration of the passage therefore requires the coolant to be circulated at high pressure to be able to cool the paddle efficiently. In addition, the blade 4 is integrally formed with the shaft, and is not adapted for K-mixers, for which blades must sometimes be replaced. Furthermore, agitators typically have a single blade and are subject to low intensity loads with a single blade integrally formed at the end of the shaft, oriented in the direction of the shaft. Conversely, K-mixers have typically a plurality of blades that are perpendicular to the shaft which rotate at high RPMs and generate high moments of force.
In view of the above, there is thus a need for an improved K-mixer that would be able to overcome or at least minimize some of the above-discussed concerns. It would be desirable for the improved K-mixer to allow a temperature control of the shaft and of the independent blade(s), and to improve flow of a heat transfer fluid within the shaft assembly and the blade assembly so as to increase heat transfer exchanges. Furthermore, there is also a need for a K-mixer which would facilitate replacement of the blades when the hard facing begins to wear down, and additionally would allow for a custom blade design and replacement. Additionally, a K-mixer allowing temperature control of each blade individually would prove beneficial.